Alanine transferase: An independent indicator of adiposity related comorbidity risk in youth

Background Elevated levels of alanine aminotransferase (ALT) are associated with obesity and are often a consequence of non-alcoholic fatty liver disease (NAFLD). The aim of the present study was to assess the relationship between ALT and risk factors for adiposity-related co-morbidities in a diverse population of middle school children. Methods We measured height, weight, body fatness (bioelectrical impedance), waist circumference, insulin sensitivity, phase 1 insulin release (acute insulin response following intravenous glucose), beta-cell function (acute insulin response corrected for insulin sensitivity), ALT, lipid profiles, and circulating concentrations of interleukin-6 (IL-6), C-reactive protein, adiponectin, and tumor necrosis factor-α (TNF-α) in a multi-ethnic/racial population of 106 middle school students (aged 11–14 years, 45 female) of varying body mass indexes (BMI). Results Alanine aminotransferase was significantly correlated with BMI, % body fat, fat mass, waist circumference, fasting insulin, insulin resistance, triglycerides, and was inversely correlated with high-density lipoprotein cholesterol in children, even though all values of ALT were “normal” (range of 4.0–33.0 U/L). ALT was significantly higher in males than females even when corrected for body fatness. Significant correlations with lipids and insulin resistance persisted even when adjusted for age, gender, and body fatness. Conclusion Even within the normative range, ALT levels were significantly correlated with anthropomorphic and biochemical risk factors for adiposity-related co-morbidities in youth. Therefore, because ALT is correlated with dyslipidemia, insulin resistance, and central fat distribution, it might also serve as a marker of risk for adiposity-related co-morbidities beyond NAFLD. 摘要 背景： 丙氨酸氨基转移酶（alanine aminotransferase，ALT）水平升高与肥胖相关，这通常是非酒精性脂肪性肝病（non-alcoholic fatty liver disease，NAFLD）的结果。这项研究的目的是在不同的中学儿童人群中评估ALT与肥胖相关合并症危险因素之间的关系。 方法： 我们在106名体重指数（BMI）不同的多种族/人种中学生人群（年龄为11–14岁，有45名女性）中测量了身高、体重、体脂（生物电阻抗）、腰围、胰岛素敏感性、1相胰岛素释放（静脉注射葡萄糖后的急性胰岛素反应）、β-细胞功能（校正胰岛素敏感性后的急性胰岛素反应）、ALT、血脂谱、循环中的白细胞介素-6（IL-6）、C-反应蛋白、脂联素以及肿瘤坏死因子-α（TNF-α）浓度。 结果： 在儿童中，ALT与BMI、体脂百分比、脂肪含量、腰围、空腹胰岛素、胰岛素抵抗、甘油三酯显著相关，并且与高密度脂蛋白胆固醇负相关，即使所有的ALT值都是“正常的”（范围为4.0–33.0 U/L）。即便校正体脂后，男性ALT仍显著高于女性。血脂与胰岛素抵抗之间存在显著的相关性，即便在校正年龄、性别与体脂之后。 结论： 在年轻人中，即使ALT水平处在标准范围，它仍然与肥胖相关合并症的人体测量学以及生化危险因素显著相关。因此，由于ALT与血脂异常、胰岛素抵抗以及中心性脂肪分布相关，所以除了NAFLD之外它还可以作为一个肥胖相关合并症风险的标志物。